For many products, susceptibility to shock damage is not merely determined by the amount of energy in the shock, but also the frequency content of that shock. These are typically products in which the internal resonances play a significant role in damaging the product. For example, disk drive mechanisms are highly susceptible to shock damage. In fact, one of the many failure modes in a disk drive is disk media surface damage due to the arm tip striking the disk surface, leading to possible loss of data and/or a catastrophic head crash. Since disk drives are very tightly built, actuator arm tips are nominally only about 0.008 inches above the disk surface, and are commonly even much closer due to manufacturing tolerances. As such, a shock pulse with a frequency content that matches the arm resonance, for instance, will cause higher displacements of the arm tips than a shock pulse of lower frequency (total energy being equal). To this regard, the fundamental frequency content of a shock pulse can be estimated by taking the inverse of the pulse duration doubled. A doubling of duration will drop the fundamental frequency content in half.
These shock pulses may be especially damaging in connection with enclosures or modules that house multiple disk drive mechanisms. Often multiple drive mechanisms are housed in a single enclosure to implement modular disk array architectures and data redundancy schemes such as those known in redundant arrays of inexpensive disks (RAID) configurations. Enclosures that house multiple disk drives are especially subject to shock pulses (or shock waves) as they are loaded and unloaded in transit from manufacturer to retailer to customer, and during normal placement (i.e., lifting, dropping or tilt dropping) into position for use by the customer, because of the generally bulky size and extra weight associated with the enclosure due to the multiple mechanisms therein. As such, damage may occur not only to one but to several potentially costly mechanisms in the form of media damage, spindle damage, etc.
Accordingly, an object of the present invention is to provide improved shock protection for shock sensitive mechanisms and, especially, for arrays of such mechanisms that are housed in a single enclosure. Further objects are to provide shock protection at essentially no additional cost and with no additional parts to the enclosure.